F. Fandrich et al., INDUCTION OF RAT-LIVER MICROSOMAL EPOXIDE HYDROLASE BY ITS ENDOGENOUSSUBSTRATE 16-ALPHA, 17-ALPHA-EPOXYESTRA-1,3,5-TRIEN-3-OL, Xenobiotica, 25(3), 1995, pp. 239-244
1. The influence of the endogenous steroid epoxides 16 alpha, 17 alpha
-epoxyestra-1,3,5(10)-trien-3-ol (estroxide) and 16 alpha, 17 alpha-ex
poxiandrost-4-en-3-one (androstene oxide) and their metabolic precurso
rs estra-1,3,5(10), 16-tetraen-3-ol (estratetraenol) and androsta-4, 1
6-dien-3-one (androstadienone) on the specific activities of hepatic m
icrosomal and soluble epoxide hydrolase, glutathione S-transferase, di
hydrodiol dehydrogenase, and 7-ethoxycoumarin deethylase was investiga
ted in the male Sprague-Dawley rat. 2. Both estroxide and estratetraen
ol induced microsomal epoxide hydrolase activity towards styrene oxide
and estroxide itself 2-2.5-fold and glutathione conjugation of 1-chlo
ro-2,4-dinitrobenzene (CDNB) 1.6-fold after intraperitoneal administra
tion of a high dose of compound (300 mg per kg of body weight). 3. In
addition, estroxide decreased 7-ethoxycoumarin deethylation down to 20
% of the activity observed in the untreated rat, whereas estratetraeno
l enhanced the activity of soluble epoxide hydrolase towards trans-sti
lbene oxide by a factor of 1.7. 4. In contrast, neither androstene oxi
de nor androstadienone showed a significant influence on any of the pa
rameters under investigation. Dihydrodiol dehydrogenase was not signif
icantly changed by any of the treatments.